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| United States Patent |
5,159,014
|
|
Tsutsumi
, et al.
|
October 27, 1992
|
Thermoplastic elastomer composition and rubber parts of refrigerator
having a layer composed of thermoplastic elastomer composition
Abstract
A thermoplastic elastomer composition comprising (a) 20 to 70 parts by
weight of a polyamide and (b) 80 to 30 parts by weight of a butyl rubber
modified with a functional-group-containing compound having at least one
group selected from a carboxyl group, an acid anhydride group and an epoxy
group as the functional group, the total amount of the (a) and (b)
components being 100 parts by weight. The thermoplastic elastomer
composition is resistant to permeation of FREON gases containing hydrogen
atom in their molecules and has excellent flexibility, low-temperature
resistance and oil resistance.
| Inventors:
|
Tsutsumi; Fumio (Yokkaichi, JP);
Morikawa; Akihiko (Yokkaichi, JP);
Hasegawa; Mamoru (Yokkaichi, JP);
Oshima; Noboru (Suzuka, JP)
|
| Assignee:
|
Japan Synthetic Rubber Co., Ltd. (Tokyo, JP)
|
| Appl. No.:
|
409293 |
| Filed:
|
September 19, 1989 |
Foreign Application Priority Data
| Sep 20, 1988[JP] | 63-233782 |
| Current U.S. Class: |
525/66; 525/179 |
| Intern'l Class: |
C08L 077/00 |
| Field of Search: |
525/66,179
|
References Cited
U.S. Patent Documents
| 2914496 | Jul., 1959 | Kelly | 525/184.
|
| 4987017 | Jan., 1991 | Sato et al. | 525/179.
|
| Foreign Patent Documents |
| 57-070139 | Apr., 1982 | JP.
| |
| 63-221182 | Sep., 1988 | JP.
| |
| 63-238159 | Oct., 1988 | JP.
| |
| 1518639 | Jul., 1978 | GB.
| |
| 1552352 | Sep., 1979 | GB.
| |
Primary Examiner: Carrillo; Ana L.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Claims
What is claimed is:
1. A thermoplastic elastomer composition having excellent flexibility and
balance of oil resistance, low-temperature resistance, and resistance to
permeation by fluorocarbons, consisting essentially of;
(a) 20 to 70 parts by weight of a polyamide, and
(b) 80 to 30 parts by weight of a butyl rubber modified with from 1 to 50
milliequivalents per 100 grams of said butyl rubber of a member selected
from the group consisting of .alpha.,.beta.-ethylenically unsaturated
carboxylic acids; .alpha.,.beta.-ethylenically unsaturated carboxylic
anhydrides; glycidyl esters of .alpha.,.beta.-ethylenically unsaturated
carboxylic acids; and alkenyl glycidyl ethers, the total amount of the (a)
and (b) components being 100 parts by weight.
2. The thermoplastic elastomer composition according to claim 1, wherein
the polyamide (a) is a member selected from the group consisting of nylon
6, nylon 6,6, nylon 11, nylon 12, nylon 6,9, nylon 6,10, nylon 4,6 and
nylon 1,12.
3. The thermoplastic elastomer composition according to claim 1, wherein
the polyamide (a) is nylon 11, nylon 12, nylon 6 or nylon 4,6.
4. The thermoplastic elastomer composition according to claim 1, wherein
the polyamide (a) is nylon 11 or nylon 12.
5. The thermoplastic elastomer composition according to claim 1, wherein
the butyl rubber (b) is that prepared by dehydrohalogenating a halogenated
butyl rubber with a dehydrohalogenating agent to prepare a conjugated
diene unit-containing butyl rubber and then subjecting the conjugated
diene unit-containing butyl rubber to addition reaction in the absence of
a peroxide catalyst with a functional group-containing compound selected
from the group consisting of .alpha.,.beta.-ethylenically unsaturated
carboxylic acids; .alpha.,.beta.-ethylenically unsaturated dicarboxylic
anhydrides; glycidyl esters of .alpha.,.beta.-ethylenically unsaturated
carboxylic acids; and alkenyl glycidyl ethers.
6. The thermoplastic elastomer composition according to claim 1, wherein
the amount of the polyamide (a) is 25 to 60 parts by weight and the amount
of the butyl rubber (b) is 75 to 40 parts by weight.
7. The thermoplastic elastomer according to claim 1, wherein the amount of
the polyamide (a) is 30 to 55 parts by weight and the amount of the butyl
rubber (b) is 70 to 45 parts by weight.
8. A thermoplastic elastomer composition according to claim 1, wherein the
.alpha.,.beta.-ethylenically unsaturated carboxylic acids are selected
from the group consisting of maleic acid, acrylic acid, methacrylic acid,
itaconic acid, monoethyl maleate, fumaric acid, monoethyl fumarate,
vinylbenzoic acid, vinylphthalic acid, monoethyl itaconate and maleic
monoamilide; the .alpha.,.beta.-ethylenically unsaturated dicarboxylic
anhydrides are selected from the group consisting of maleic anhydride,
itaconic anhydride, and vinylphthalic anhydride; the glycidyl esters of
.alpha.,.beta.-ethylenically unsaturated carboxylic acids are selected
from the group consisting of glycidyl methacrylate, glycidyl acrylate,
monoglycidyl itaconate and diglycidyl itaconate; and the alkenyl glycidyl
ethers are selected from the group consisting of allyl glycidyl ether and
vinyl glycidyl ether.
9. A thermoplastic elastomer composition having excellent flexibility and
balance of oil resistance, low-temperature resistance, and resistance to
permeation by fluorocarbons, consisting essentially of:
(a) 20 to 70 parts by weight of nylon 11, and
(b) 80 to 30 parts by weight of a butyl rubber modified with from 1 to 50
milliequivalents per 100 grams of said butyl rubber of a member selected
from the group consisting of .alpha.,.beta.-ethylenically unsaturated
carboxylic acids; .alpha.,.beta.-ethylenically unsaturated dicarboxylic
anhydrides; glycidyl esters of .alpha.,.beta.-ethylenically unsaturated
carboxylic acids; and alkenyl glycidyl ethers, the total amount of the (a)
and (b) components being 100 parts by weight.
10. A thermoplastic elastomer composition according to claim 9, wherein the
.alpha.,.beta.-ethylenically unsaturated carboxylic acids are selected
from the group consisting of maleic acid, acrylic acid, methacrylic acid,
itaconic acid, monoethyl maleate, fumaric acid, monoethyl fumarate,
vinylbenzoic acid, vinylphthalic acid, monoethyl itaconate and maleic
monoanilide; the .alpha.,.beta.-ethylenically unsaturated dicarboxylic
anhydrides are selected from the group consisting of maleic anhydride,
itaconic anhydride, and vinylphthalic anhydride; the glycidyl esters of
.alpha.,.beta.-ethylenically unsaturated carboxylic acids are selected
from the group consisting of glycidyl methacrylate, glycidyl acrylate,
monoglycidyl itaconate and diglycidyl itaconate; and the alkenyl glycidyl
ethers are selected from the group consisting of allyl glycidyl ether and
vinyl glycidyl ether.
Description
This invention relates to a thermoplastic elastomer composition which is
rich in flexibility and excellent in balance of oil resistance,
low-temperature resistance and resistance to permeation of FREON gases
(fluorocarbons) and the like, and particularly to a thermoplastic
elastomer composition suitable for use in rubber parts of a refrigerator.
As a refrigerant for air-conditioner in automobiles, FREON gases
R-12(CCl.sub.2 F.sub.2) , R-11(CCl.sub.3 F) and R-113(CCl.sub.2
F-CCl.sub.2 F) have heretofore been generally used. However, recently, it
has been clarified that FREON gases R-12, R-11 and R-113 break the
ozonosphere in the upper atmosphere and regulation of use of FREON gases
R-12, R-11 and R-113 is being internationally strengthened.
As a countermeasure therefor, the change of the refrigerant from FREON
gases R-12, R-11 and R-113 to CF.sub.4 and easily decomposable FREON gases
containing hydrogen atom in their molecules (hereinafter referred to as
hydrogen-containing FREON gases) such as FREON gases R-22(CHClF.sub.2),
R-142b(CH.sub.3 CClF.sub.2), R-134a(CF.sub.3 CH.sub.2 F), R-123(CF.sub.3
CHCl.sub.2), R-152a(CH.sub.3 CHF.sub.2), R-141b(CH.sub.3 CCl.sub.2 f),
R-133a(CF.sub.3 CH.sub.2 Cl), R-143a(CH.sub.3 CF.sub.3) and the like is in
progress.
However, hydrogen-containing FREON gases such as FREON gases R-22, R-142b,
R-134a and the like have a greater permeation ability to a material
consisting of an elastomer than FREON gas R-12 and the like, and
vulcanized rubbers comprising a nitrile rubber as a main component which
have conventionally been used for FREON gas R-12 and the like are not
satisfactory in ability to seal hydrogen-containing FREON gases R-22,
R-142b, R-134a and the like.
Therefore, use of a metal tube for hydrogen-containing FREON gases such as
FREON gases R-22, R-142b, R-134a and the like is taken into consideration;
however, this has such problems that noise is made by vibration during the
running of a car and the degree of freedom of piping layout in a bonnet is
reduced.
Also, the use of resin hoses consisting essentially of nylon is under
consideration; however, there are problems similar to those in the case of
use of a metal tube. Therefore, there has been desired development of a
rubber material for sealing FREON gases which has flexibility and
excellent resistance to permeation of hydrogen-containing FREON gases such
as FREON gases R-22, R-142b, R-143a and the like.
In addition, attempts have been made to blend a flexible elastomer with a
resin such as nylon to obtain a balance of resistance to FREON
gas-permeation and flexibility; however, when a satisfactory flexibility
has been achieved the resistance to FREON gas-permeation has become
insufficient and when satisfactory resistance to FREON gas-permeation has
been achieved the flexibility has become insufficient. Thus, it has been
difficult to satisfy the two properties simultaneously.
An object of this invention is to provide a thermoplastic elastomer
composition having a flexibility and excellent resistance to permeation of
FREON gases containing hydrogen atom in their molecules such as FREON
gases R-22, R-142b, R-143a and the like.
Other objects and advantages of this invention will become apparent from
the following description and the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIGS. 1A and 1B show a FREON gas-permeation tester as used in the examples,
wherein 1 refers to a stainless steel cup, 2 to a stainless steel lid, 3
to a punching board having a permeation area of 1.16 cm.sup.2, 4 to a test
piece of 2 mm in thickness, and 5 to a bolt and 6 to a nut. FIG. 1A shows
a frontal view of the stainless steel lid of the FREON gas-permeation
tester and FIG. 1B shows an exploded side view of the FREON gas-permeation
tester.
According to this invention, there is provided a thermoplastic elastomer
composition which comprises (a) 20 to 70 parts by weight of a polyamide
and (b) 80 to 30 parts by weight of a butyl rubber modified with a
functional-group-containing compound having at least one group selected
from a carboxyl group, an acid anhydride group and an epoxy group as the
functional group (hereinafter referred to as the functional
group-containing compound), the total amount of the (a) and (b) components
being 100 parts by weight (the butyl rubber modified with the
functional-group-containing compound is hereinafter referred to as merely
the modified butyl rubber).
The polyamide (a) used in this invention includes nylon 6, nylon 6,6, nylon
11, nylon 12, nylon 6,9, nylon 6,10, nylon 4,6, nylon 6,12 and the like,
among which nylon 11, nylon 12, nylon 6 and nylon 4,6 are preferable and
nylon 11 and nylon 12 are more preferable.
The polyamide (a) may also be a polyamide obtained by copolymerizing
different monomers, namely a polyamide elastomer synthesized by
condensation of a polyether with a polyamide.
The modified butyl rubber (b) used in this invention is a butyl rubber
having, as a modifying group, a carboxyl group, an acid anhydride group
and/or an epoxy group. The modified butyl rubber may be prepared by (1) a
method which comprises adding, to a butyl rubber or a halogenated butyl
rubber, a functional-group-containing compound selected from an
.alpha.,.beta.-ethylenically unsaturated carboxylic acid, an
.alpha.,.beta.-ethylenically unsaturated carboxylic anhydride, an
.alpha.,.beta.-ethylenically unsaturated carboxylic epoxide and an alkenyl
glycidyl ether in the presence of a peroxide, (2) a method which comprises
adding, to a butyl rubber, an alkali metal such as lithium, potassium,
sodium or the like, and then adding thereto a functional group-containing
compound selected from an .alpha.,.beta.-ethylenically unsaturated
carboxylic acid, an .alpha.,.beta.-ethylenically unsaturated carboxylic
anhydride, an .alpha.,.beta.-ethylenically unsaturated carboxylic epoxide
and an alkenyl glycidyl ether or (3) a method which comprises
dehydrohalogenating a halogenated butyl rubber with a dehydrohalogenating
agent such as a metal which has been subjected to metal
alcoholate-reduction, ZnO/RCOOH, (RCOO).sub.2 -Zn/RCOOH/CaO in which R is
an alkyl group having 1 to 8 carbon atoms, an aralkyl group or an aryl
group (the same applies hereinafter), CuO, (RCOO).sub.2 -Zn or the like to
prepare a conjugated diene unit-containing butyl rubber and then adding
thereto a functional-group-containing compound selected from an
.alpha.,.beta.-ethylenically unsaturated carboxylic acid, an
.alpha.,.beta.-ethylenically unsaturated carboxylic anhydride, an
.alpha.,.beta.-ethylenically unsaturated carboxylic epoxide and an alkenyl
glycidyl ether.
The modified butyl rubber (b) used in this invention is preferably prepared
by the above method (3) in which the conjugated diene unit-containing
butyl rubber is used.
The method of preparing the conjugated diene unit-containing butyl rubber
is disclosed in U.S. Pat. No. 3,965,213, Japanese Patent Application Kokai
Nos. 48-08385, 53-42289 and 59-84901, Japanese Patent Application Kokoku
No. 57-14363 and the like.
The functional group-containing compound used for modification of a butyl
rubber in the preparation of the modified butyl rubber (b) includes
.alpha.,.beta.-ethylenically unsaturated carboxylic acids such as maleic
acid, acrylic acid, methacrylic acid, itaconic acid, monoethyl maleate,
fumaric acid, monoethyl fumarate, vinylbenzoic acid, vinylphthalic acid,
monoethyl itaconate, maleic monoanilide and the like;
.alpha.,.beta.-ethylenically unsaturated carboxylic anhydrides such as
anhydrides of the above-mentioned ethylenically unsaturated carboxylic
acids, for example, maleic anhydride and the like;
.alpha.,.beta.-ethylenically unsaturated carboxylic epoxides such as
glycidyl methacrylate, glycidyl acrylate, monoglycidyl itaconate,
diglycidyl itaconate and the like; and alkenyl glycidyl ethers such as
allyl glycidyl ether, vinyl glycidyl ether and the like.
In the preparation of the modified butyl rubber used in this invention, for
example, the above-mentioned conjugated diene unit-containing butyl rubber
is reacted with the functional-group-containing compound in the absence of
a solvent or in the presence of an organic solvent such as n-hexane,
toluene, cyclohexane, heptane, xylene or the like at a temperature of from
room temperature to 300.degree. C. In this reaction, a small amount of an
organic peroxide such as benzoyl peroxide or the like may be used. This
reaction may be conducted in a reactor provided with a stirring blade, a
Banbury mixer, a kneader or the like.
The amount of the carboxyl group, acid anhydride group and/or epoxy group
to be introduced into the butyl rubber is 1 to 50 milliequivalents,
preferably 2 to 20 milliequivalents, per 100 g of the butyl rubber. When
the amount of the functional group introduced is too small, the
blendability of the modified butyl rubber (b) with the polyamide (a)
becomes inferior and the composition obtained becomes inferior in
resistance to permeation of hydrogen-containing FREON gases. When the
amount is too high, the composition obtained becomes inferior in
flexibility.
The thermoplastic elastomer composition of this invention comprises (a) a
polyamide and (b) the modified butyl rubber as the essential components,
and the weight ratio of the (a) component to the (b) component is
20/80-70/30, preferably 25/75-60/40, more preferably 30/70-55/45. When the
amount of the modified butyl rubber (b) is more than 80 parts by weight,
the composition obtained has too low strength to be used in rubber parts
of a refrigerator and also is inferior in oil resistance and moldability.
On the other hand, when the amount of the modified butyl rubber (b) is
less than 30 parts by weight, it is impossible to obtain the desired
flexibility.
The composition of this invention may comprise, in addition to (a) a
polyamide and (b) the modified butyl rubber, not more than about 50 parts
by weight, per 100 parts by weight of the modified butyl rubber, of
chloroprene, chlorinated polyethylene, polyisoprene, natural rubber, an
ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer
rubber, polybutadiene rubber, chlorosulfonated polyethylene, an
epichlorohydrin rubber, a halogenated ethylene-propylene rubber,
ethylene-butene copolymer or the like.
The thermoplastic elastomer composition of this invention may further
comprise a filler in a proportion of preferably 20-200 parts by weight,
more preferably 30-180 parts by weight, per 100 parts by weight of the
composition.
The filler mentioned above includes carbon black, silica, calcium carbonate
and mica which have a surface area of 10 to 300 m.sup.2/ g (ASTM D3707)
and a capability of absorbing dibutyl phthalate (DBP) in a proportion of
20-150 cc/100 g and further finely divided quartz, diatomaceous earth,
zinc oxide, basic magnesium carbonate, calcium metasilicate, titanium
dioxide, talc, aluminum sulfate, calcium sulfate, barium sulfate,
asbestos, glass fiber, organic reinforcing agents, organic fillers and the
like. Particularly, the above-mentioned carbon black, silica, calcium
carbonate and mica are preferred. Also, in the case of an inorganic
filler, a silane-coupling agent may be co-used to increase the modulus of
crosslinked product.
These fillers may be used alone or in combination of two or more.
The thermoplastic elastomer composition of this invention may further
comprise other various additives which are conventionally used. These
additives may be added in the course of or after the preparation of the
thermoplastic elastomer composition of this invention.
The thermoplastic elastomer composition may comprise, in any combination, a
dispersing assistant such as a higher fatty acid, a metal salt or amine
salt thereof: a plasticizer such as polydimethylsiloxane oil,
diphenylsilanediol, trimethylsilanol, a phthalic acid derivative or an
adipic acid derivative; a softening agent such as a lubricating oil,
process oil, coal tar, castor oil or calcium stearate; an antioxidant such
as a phenylenediamine, a phosphate, a quinoline, a cresol, a phenol or a
metal dithiocarbamate; a heat-resisting agent such as iron oxide, cerium
oxide, potassium hydroxide, iron naphthenate or potassium naphthenate; a
coloring agent; an ultraviolet absorber; a flame-retardant; an
oil-resistance-improver; an antiscorching agent; a tackifier; a lubricant
and the like.
The thermoplastic elastomer composition of this invention can be prepared
by melt-mixing (a) a polyamide and (b) the modified butyl rubber by means
of an internal mixer such as roll, Banbury mixer, press-kneader or the
like or a kneading machine such as extruder or the like.
In this case, it is possible to add a cross-linking agent for the modified
butyl rubber such as a combination of an organic peroxide with a
crosslinking assistant; a resin type crosslinking agent; quinonedioxide;
nitrobenzene; tetrachloroquinone; a diamin; a combination of sulfur with a
vulcanization accelerator and a vulcanizing assistant; or the like,
melt-mix them to prepare a crosslinkable elastomer composition and
thereafter subject the resulting mixture to molding and crosslinking under
the conventional conditions to prepare a crosslinked product. Also,
ultraviolet crosslinking is possible.
The organic peroxide includes, for example, dicumyl peroxide,
2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3,
2,5-dimethyl-2,5-di(t-butylperoxy)hexane,
2,2'-bis(t-butylperoxy)-p-diisopropylbenzene, di-t-butyl peroxide,
t-butylbenzoate, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,
2,4-dichlorobenzoyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide,
t-butylperoxybenzoate, di-t-butylperoxyisophthalate and the like, and
preferred is dicumyl peroxide.
In the crosslinking with the organic peroxide, a difunctional vinyl monomer
may be used as a crosslinking assistant, and the crosslinking assistant
includes ethylene dimethacrylate, 1,3-butylene dimethacrylate,
1,4-butylene dimethacrylate, 1,6-hexanediol dimethacrylate, polyethylene
glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol
diacrylate, 2,2'-bis(4-methacryloyldiethoxyphenyl)propane,
trimethylolpropane trimethacrylate, pentaerythritol triacrylate,
divinylbenzene, N,N'-methylenebisacrylamide, p-quinonedioxime,
p,p'-dibenzoylquinonedioxime, triazinedithiol, triallyl cyanurate,
triallyl isocyanurate, m-phenylene bismaleimide, a silicone oil having a
large vinyl content, and the like.
The resin type crosslinking agent includes alkylphenol-formaldehyde resins,
brominated alkylphenolformaldehyde resins and the like.
Also, an organic crosslinking agent such as quinonedioxime, nitrobenzene,
tetrachloroquinone or the like may be used in some cases.
The diamine includes hexamethylenediamine, tetramethylenediamine,
3,3'-diphenylmethanediamine, 3,3'-dicyclohexylmethanediamine and the like.
In a blend system comprising sulfur, a vulcanizing accelerator and a
vulcanizing assistant, the vulcanizing accelerator includes guanidines,
thioureas, thiazoles, dithiocarbamates, xanthates and thiurams, and a
mixing accelerator is also used.
The vulcanizing assistant, namely, a vulcanization-accelerating assistant
or an activator, includes metal hydroxides such as zinc oxide, magnesium
oxide and the like; a metal hydroxide such as calcium hydroxide or the
like; fatty acids such as stearic acid, lauric acid, oleic acid and the
like, and the vulcanization-accelerator is used in such an amount as used
in conventional rubber blending.
The amount of the crosslinking agent or the crosslinking assistant blended
is 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight, per
100 parts by weight of the modified butyl rubber. When the amount is too
small, the crosslinking density of the rubber component becomes low and
the composition becomes inferior in mechanical strength and resistance to
permeation of hydrogen-containing FREON gases. When the amount is too
large, the crosslinking density of the rubber component becomes high and
the elongation of the resulting composition becomes low.
The thermoplastic elastomer composition of this invention is excellent in
resistance to permeation of hydrogen-containing FREON gases and, utilizing
this characteristic feature, can be appropriately used in rubber parts of
a refrigerator in which FREON gases, particularly hydrogen-containing
FREON gases, are used, the rubber parts including, for example, a hose, a
packing, a sealant and the like. For example, the hose and the packing may
have a layer composed of the thermoplastic elastomer composition of this
invention at a portion at which they contact with the refrigerant used in
a refrigerator.
This invention is further explained in more detail below referring to
Examples. In the Examples, various measurements were conducted according
to the following methods.
Physical properties of crosslinked product: Evaluated according to JIS
K6301.
Oil resistance: Measurement was effected at 100.degree. C. for 70 hours
according to JIS K6301 using a JIS No. 3 oil.
Low-temperature resistance: Evaluated by a Gehman torsion test.
FREON gas permeability: A rubber composition was kneaded with the
compounding recipe shown in Table 1 or 2, and then vulcanized to prepare a
disk-shaped sheet having a thickness of 2 mm and a diameter of 50 mm,
after which the sheet was subjected to a FREON gas permeation test using a
FREON gas permeation tester as shown in FIG. 1.
EXAMPLES 1-15 AND COMPARATIVE EXAMPLES 1-5
Preparation of Modified Butyl Rubber
Modified Butyl Rubber A
In a 3-liter flask, 100 g of chlorinated butyl rubber having a chlorine
content of 1.2% by weight (JSR Butyl 1068, a trade name of Japan Synthetic
Rubber, Co., Ltd.) was dissolved in 1,000 g of toluene in a nitrogen gas
stream.
Subsequently, 3 g of zinc oxide and 2 g of 2-ethylhexanoic acid were added
to the resulting solution, and thereafter, the resulting mixture was
subjected to reaction for 2 hours under reflux conditions while removing
water. The conjugated diene content of the resulting polymer was 1 mole.
Incidentally, the conjugated diene content was determined by an
ultraviolet ray-absorption analysis.
The conjugated diene unit-containing butyl rubber was mixed with maleic
anhydride in a proportion of 0.5% by weight based on the weight of the
polymer (5 milliequivalents/100 g of polymer) at 150.degree. C. for 5
minutes in a 250-cc Brabender mixer to obtain a maleic anhydride-modified
butyl rubber.
The amount of the maleic anhydride added to the polymer was 0.4% by weight.
Modified Butyl Rubber B
The same procedure as in the preparation of Modified Butyl Rubber A was
repeated, except that the amount of maleic anhydride was varied to 2% by
weight based on the weight of the polymer (20.4 milliequivalents/100 g of
polymer), to obtain a maleic anhydride-modified butyl rubber.
The amount of the maleic anhydride added to the polymer was 1.5% by weight.
Modified Butyl Rubber C
The same procedure as in the preparation of Modified Butyl Rubber A was
repeated, except that the amount of maleic anhydride was varied to 0.2% by
weight based on the weight of the polymer (2 milliequivalents/100 g of
polymer) to prepare a maleic anhydride modified butyl rubber.
The amount of the maleic anhydride added to the polymer was 0.2% by weight.
Modified Butyl Rubber D
The same procedure as in the preparation of Modified Butyl Rubber A was
repeated, except that 2.0% by weight of methacrylic acid (23.3
milliequivalents/100 g of polymer) was substituted for the 0.5% by weight
of maleic anhydride and the mixing was conducted at 150.degree. C. for 20
minutes, to obtain an acrylic acid-modified butyl rubber.
The amount of the acrylic acid added to the polymer was 0.8% by weight.
Modified Butyl Rubber E
The same procedure as in the preparation of Modified Butyl Rubber A was
repeated, except that 2.0% by weight of glycidyl methacrylate (14
milliequivalents/100 g of polymer) was substituted for the 0.5% by weight
of maleic anhydride and the mixing was conducted at 150.degree. C. for 20
minutes, to obtain a glycidyl methacrylate-modified butyl rubber.
The amount of the glycidyl methacrylate added to the polymer was 0.7% by
weight
Modified Butyl Rubber F
To 100 parts by weight of a butyl rubber (JSR IIR 365, a trade name of
Japan Synthetic Rubber Co., Ltd.) were added 0.5 part by weight of maleic
anhydride and 0.3 part by weight of an organic peroxide (dicumyl
peroxide), and the resulting mixture was subjected to mixing at
150.degree. C. for 15 minutes to obtain a maleic anhydride-modified butyl
rubber. The amount of the maleic anhydride added to the polymer was 0.3%
by weight.
Preparation of Composition and Crosslinked Product
(1) Nylon 11 (RILSAN BESNO, a trade name of TORAY INDUSTRIES, INC.) and
nylon 12 (RILSAN AESNO, a trade name of TORAY INDUSTRIES, INC.) as
polyamides and one of the Modified Butyl Rubbers A to E as the modified
butyl rubber were melt-mixed with the compounding recipe 1 shown in Table
1 in an internal mixer (HAAKE RHEOCORD SYSTEM 40 RHEOMIX MIXER 3000
manufactured by Haake Buchler) at 200.degree. C. for 10 minutes, and the
resulting mixture was pressed at 200.degree. C. for 10 minutes by an
electrically heated press to prepare a sheet of 2 mm (thickness).times.20
mm (width).times.20 mm (length).
In Comparative Example 5, the compounding recipe 2 shown in Table 2 was
used.
The sheets thus obtained were evaluated for physical properties.
The results obtained are shown in Table 3.
TABLE 1
______________________________________
Compounding recipe 1 (parts by weight)
Methy-
lene-bis-
Di-
Sam- Ny- Ny- Modified
Carbon
cyclo- cumyl Mag-
ple lon lon butyl black hexyl- pero- nesium
No. 11 12 rubber N339 amine xide oxide
______________________________________
1 50 -- A (50) -- 2 -- --
2 70 -- A (30) -- 2 -- --
3 40 -- A (60) -- 2 -- --
4 -- 50 A (50) -- 2 -- --
5 50 -- A (50) 10 2 -- --
6 50 -- A (50) -- -- 0.5 --
7 50 -- B (50) -- 2 -- --
8 50 -- C (50) -- 2 -- --
9 50 -- D (50) -- 2 -- --
10 50 -- E (50) -- 2 -- --
11 50 -- F (50) -- 2 -- --
12 50 -- A (50) -- -- -- 5
13 50 -- A (50) -- -- -- --
14 50 -- JSR -- 2 -- 5
Butyl
1068 (50)
15 15 -- A (85) -- 2 -- --
16 80 -- A (20) -- 2 -- --
17 100 -- -- -- -- -- --
______________________________________
TABLE 2
______________________________________
Compounding receipt 2 100 parts by weight
NBR (JSR N222L, a trade name of
Japan Synthetic Rubber Co., Ltd.)
MT black 50 parts by weight
SRF black 80 parts by weight
Zinc oxide (ZnO) 5 parts by weight
Stearic acid 1 parts by weight
Polyester-based plasticizer*.sup.1
2 parts by weight
Antioxidant*.sup.2 0.5 parts by weight
Sulfur 1.0 parts by weight
Vulcanizing accelerator*.sup.3
0.4 parts by weight
NOCCELER TT
(tetramethylthiuram disulfide)
NOCCELER CZ
(N-cyclohexyl-2-benzothiazyl
0.5 parts by weight
sulfenamide)
______________________________________
Note:
*.sup.1 RS 107, a trade name of Adeka Argus Chemical Co., Ltd.
*.sup.2 NOCRAC 810NA, a trade name of Ohuchishinko Kagaku Kogyo K.K. for
Nphenyl-N'-isopropyl-p-phenylene diamine.
*.sup.3 Products of Ohuchishinko Kagaku Kogyo K.K. Vulcanization:
Pressvulcanized at 150.degree. C. for 20 minutes.
TABLE 2
__________________________________________________________________________
FREON gas
permeability
100% Tensile
Elonga- Resist-
Low temp.
(Kind of
Modulus
strength
tion Hard-
ance
resistance
FREON gas)
Sample
(M.sub.100)
(T.sub.B)
(E.sub.B)
ness
.DELTA.V
T.sub.5 /T.sub.10
(mg .multidot. mm/
No. (kg/cm.sup.2)
(kg/cm.sup.2)
(%) (H.sub.S)
(%) (.degree.C.)
cm.sup.2 .multidot. day)
__________________________________________________________________________
Example
1 1 210 350 270 99 8.0 <-70/<-70
12 (R22)
2 2 240 360 250 100 7.0 -70/<-70
8 (R22)
3 3 170 220 220 95 11.0
-55/<-70
15 (R22)
4 4 205 330 240 98 8.0 -67/<-70
14 (R22)
5 5 250 300 240 99 6.0 -67/<-70
9 (R22)
6 6 220 290 220 99 7.5 -67/<-70
13 (R22)
7 7 280 360 270 99 6.0 -68/<-70
8 (R22)
8 8 160 210 220 98 12.0
<-70/<-70
16 (R22)
9 9 155 205 180 99 13.0
<-70/<-70
25 (R22)
10 10 152 195 185 98 15.0
<-70/<-70
27 (R22)
11 11 165 200 190 99 13.0
<-70/<-70
20 (R22)
12 12 210 300 220 99 10.0
<-70/<-70
12 (R22)
13 13 -- -- -- -- -- -- 3 (R134a)
14 14 -- -- -- -- -- -- 5 (R142b/R22 =
50/50)
15 15 171 230 220 99 13.0
<-70/<-70
20 (R22)
Comp. Example
1 14 154 193 160 99 11.0
<-70/<-70
42 (R22)
2 15 25 80 120 87 21.0
-47/-57 85 (R22)
3 16 270 390 320 100 4.5 Unmeasure-
8 (R22)
able
4 17 350 420 350 100 3.1 Unmeasure-
7 (R22)
able
5 NBR 73 185 350 85 8.0 -10/<-14
12 (R12)
__________________________________________________________________________
As is clear from Table 3, the present compositions in Examples 1 to 15 are
superior in resistance to permeation of hydrogen-containing FREON gases to
the compositions in Comparative Examples 1 and 2, and have a good balance
of low-temperature resistance and tensile characteristics.
In Comparative Examples 3 and 4, the composition are rich in nylon and
consists of nylon alone, respectively, and hence, are inferior in
low-temperature resistance and not suitable for use in vibration parts.
Comparative Example 5 is for showing the FREON gas-permeability of a
nitrile rubber (acrylonitrile-butadiene rubber, NBR) composition using
FREON gas R-12 and the physical properties of the nitrile rubber
composition.
It is seen that the hydrogen-containing FREON gas-permeabilities of the
present compositions in the Examples are equivalent to the hydrogen-free
FREON gas-permeability of the NBR composition, and the low-temperature
resistance, oil resistance and tensile characteristics of the present
composition are also equivalent to those of the NBR composition.
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